Dental implants with fixed prosthodontics in oligodontia: A retrospective cohort study with a follow-up of up to 25 years

Statement of problem. Long-term assessments of implant survival and treatment outcome in patients with oligodontia are lacking. Purpose. The purpose of this retrospective clinical study was to assess which factors determine a long-term implant survival and treatment outcome of up to 25 years in a cohort of patients with oligodontia. Material and methods. The medical records of all patients with oligodontia treated with fixed implant prosthodontics between January 1991 and December 2015 in the Department of Oral and Maxillofacial Surgery at the University Medical Center Groningen, the Netherlands, were assessed. Specifically, this involved the retrieval of records on the need for and mode of bone augmentation, implant survival, and survival of and adverse events associated with the prosthodontics. The Kaplan-Meier estimator was used to analyze implant and superstructure survival. Log-rank tests were used to compare the survival of subgroups. Results. A total of 126 patients with oligodontia were treated with dental implants. Of the 777 implants in total, 56 were lost, resulting in a 5-year cumulative survival of 95.7% (95% confidence interval [CI], 94.2% to 97.2%) and a 10-year cumulative survival of 89.2% (95% CI, 86.2% to 92.2%). The survival of implants placed in regions where bone augmentation surgery had been performed was significantly lower. The 5-year cumulative superstructure survival was 90.5% (95% CI, 87.6% to 93.5%), and the 10-year cumulative superstructure survival was 80.3% (95% CI, 75.3% to 85.3%). The performance of the screw-retained and cemented superstructures was comparable, but the survival of single crowns was significantly higher than the survival of fixed partial dentures (P<.001). Conclusions. Implant treatment is a predictable treatment option for patients with oligodontia with a favorable long-term outcome. Survival of implants in augmented areas is lower.